Facsimile and static presentation processing – Static presentation processing – Attribute control
Patent
1985-10-15
1987-04-21
Shepperd, John W.
Facsimile and static presentation processing
Static presentation processing
Attribute control
358 17, H04N 944, H04N 1114
Patent
active
046600744
ABSTRACT:
An improved color television transmission compatible with NTSC standards produces a controlled horizontal scan rate at about 15,768 Hz with 227 cycles of color subcarrier per line, and a controlled horizontal scan rate at about 60.070 Hz to produce frames of two interlaced fields each at a rate of about 30.035 Hz with 227.5 cycles of the color subcarrier per field phase shifted 180.degree. of the color subcarrier at the beginning of each field, thereby eliminating "chroma crawl," and reducing the size of the teeth in the "zipper" effect produced by NTSC encoded color at the edge of vertical color borders. The vertical scan rate is controlled by dividing a clock frequency of four times the color subcarrier by four to produce the color subcarrier, and dividing the clock frequency by some set of multiples to produce the horizontal scan rates with 227 cycles of color subcarrier per line plus one-half cycle.
REFERENCES:
patent: 3581011 (1971-05-01), Ward
patent: 4051532 (1977-09-01), Hilbert
patent: 4295157 (1981-10-01), Machida et al.
patent: 4500908 (1985-02-01), Mandeberg
patent: 4517587 (1985-05-01), Aizawa et al.
patent: 4558349 (1985-12-01), Sasuki
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